This invention relates to optical components of the integrated type in which one or more optical paths is defined within a body of material. The optical path(s) may for example provide connections between optical fibres, the body of material incorporating such path(s) being adapted for connection to the fibres so as to align the fibres with the path(s).
Optical components of this type are well known and various methods for their manufacture have been devised -- see for example, the following articles appearing in Volume 104, "Micro-Optics" (1988) of the Proceedings of the International Society for Optical Engineering:
"Integrated optical refractive index sensor by ion-exchange in glass" by U. Hollenbach et al; "Command cure precision cements in optics" by R. T. Murray et al;
"Charge controlled ion exchange - a way to reproducible fabrication of integrated optical components in glass" by R. Klein et al;
"Birefringence of diffused lithium niobate Z-propogating waveguides depending on titanium concentration" by D. Eberhard;
"Optical guides in CR 39 irradiated by ion beams" by B. Bennamane et al; and
"Calculated and measured refractive index profiles of Kplus exchanged glass waveguides" by K. Spenner et al.
The Murray article for instance refers to the possibility of producing a multimode waveguide by a lithographic technique using a photo-curable resin. In practice, after the waveguide precursor has been produced by photo-etching into the resin, the remaining resin is washed away and the cured component can thereafter be encapsulated or buried in a polymer. This approach, involving photo-etching has the disadvantage that the the surfaces of the waveguide structure are microscopically rough with the consequence that light losses are inevitable at the sharp but rough boundary or interface between the waveguide and the polymer in which it is subsequently embedded thereafter.
It is known from U.S. Pat. No. 3,689,264 to produce light guides by selective irradiation of suitably sensitised samples with ultra violet light after the samples have been polymerised at a temperature below 100.degree. C., irradiation being followed by ageing of the sample such that the refractive index of the irradiated region increases.